There must have been some heads in hands at the New York HQ of the self-proclaimed “first global media company to achieve carbon neutral”.

Executives at News Corp have spent several years building the company’s green credentials, under the guidance of Rupert Murdoch, only for the founder and executive chairman to suggest it may have all been a waste of time and money. “World growing greener with increased carbon,” the media mogul wrote on Twitter last Sunday. “Thirty years of satellite evidence. Forests growing faster and thicker.”

The outburst was part of a flurry of activity from Mr Murdoch on his new favourite communications platform. A little earlier his target had been the search for renewable energy and the strain it places on public spending. “Why not switch from useless renewable energy investments to real job creating infrastructure projects. Many great possibilities waiting,” he wrote.

Mr Murdoch had been moved to speak out partly by an article in his Wall Street Journal by Matt Ridley, a provocative science author and a columnist on the paper. In a piece last Saturday, headlined “The Greening of the Planet”, Ridley wrote: “Did you know that the earth is getting greener, quite literally. Satellites are now confirming that the amount of green vegetation on the planet has been increasing for three decades.”

While there may seem nothing remarkable about a free-market capitalist expressing doubts about the environmental consensus around climate change, Mr Murdoch’s tweets appear to hint at a change of heart for someone who had previously warned of the dangers of global warming.

Inspired by his mother, Dame Elisabeth – one of Australia’s most famous gardeners and a fierce climate change campaigner, who died in December aged 103 – he oversaw attempts to reduce the carbon footprint of News Corp’s global operations. The company still boasts on its website about “minimising its environmental impact, growing sustainably and inspiring others to take action”.

Nearly six years ago, Mr Murdoch stood up at the lectern in the Hudson Theatre in New York and gave a stark warning: “Climate change poses clear, catastrophic threats. We may not agree on the extent, but we certainly can’t afford the risk of inaction.”

As he signed up to a coalition of businesses and governments called the Climate Group, Mr Murdoch – standing alongside Tony Blair – talked enthusiastically of “promising new technologies – bio-fuels, solar and wind power, cleaner coal”, and urged global leaders to act fast. “The climate will not wait for us,” he said.

Rupert’s son James pioneered green policies at News Corp’s British outposts and pointedly drove to work at the company’s Wapping newspaper offices in a Toyota Prius hybrid.

At a time when he was the presumed heir to the News Corp throne, James oversaw the opening, at a cost of £350m, of “the most energy efficient print plant in the world” as well as the biggest. Meanwhile The Sun hired its first environment correspondent and the News of the World launched a campaign called “Go Green & Save”, encouraging readers to recycle their mobile phone handsets.

James’s wife, Kathryn Hufschmid, is known as a “climate hawk” and works as a public relations strategist for the Clinton Climate Initiative, set up by former President Bill Clinton.

But much has happened to Rupert Murdoch between the two public outbursts, including the death of his mother. The phone hacking scandal has also blown off course the career of James Murdoch. The company airlifted him out of London and promoted him to a job in New York.

Bob Ward, the policy and communications director at the Grantham Research Institute on Climate Change and the Environment, at the London School of Economics, said: “Under James, News International [the UK arm of News Corp] had a very clear commitment to be a carbon neutral company. It’s rather odd that [Rupert] should be expressing these views when the company is still largely making such a big thing out of it.”

But News Corp’s corporate position on climate change is very different from that of many of its news outlets. Both Fox News and the Wall Street Journal are longstanding and outspoken climate change sceptics, as are News Corp’s main Australian titles. Although The Times is less obviously critical of accepted thinking in environmental science, it has also published articles by Ridley and it currently does not have a designated environment correspondent.

A cartoonist once pictured Dame Elisabeth looking over Rupert’s shoulder as he read an attack on Australia’s carbon emissions tax in one of his own papers, and asking her son: “Do you still read that rag?”

It seems Mr Murdoch is still reading and that he shares the scepticism.